The invention relates to a wheel bearing and a constant-velocity joint, with the constant-velocity joint being arranged inside the wheel bearing, and particularly relates to the securement of these parts.
Integration of parts and, related to this, the requirement for lightweight construction is a long-standing requirement in motor vehicle construction. This also applies to the wheel bearing and to the efforts made to integrate as many wheel bearing peripheral functions as possible into the wheel bearing.
A wheel bearing with an integrated constant-velocity joint is shown in DE 2903229 A1. In this publication, the drive torque is frictionally transmitted to the inner ring flange by an axial extension of the outer part of the constant-velocity joint. The problem with this arrangement is that it does not permit precise, true guiding of the brake disk and the rim with no run-out, since both parts are centered via the axial extension of the outer part.
The object of the invention is to provide a new type of connection between the wheel bearing and the constant-velocity joint, which meets the demands for lightweight construction, is easy to manufacture in terms of production engineering and permits true positioning of the brake disk and the rim with no run-out.
The essence of the invention is that the outer part of the constant-velocity joint is axially extended and the extended part is received in the inner ring or the inner ring flange. The contours for the projections or teeth directed radially outward are then incorporated in this extension. These projections of the outer part are inserted axially into the depressions in the inner ring flange during and assembly and the projections are positively centered by these depressions. Since the area of the raceways subject to loading by the balls of the constant-velocity joint is situated at an axial distance opposite the stressed region of the inner ring flange, no constraining forces are generated in the outer part of the joint between the raceways of the constant-velocity joint, since the production tolerances in the outer part can be flexibly compensated for in operation. The brake disk and rim are centered by way of the inner ring flange and consequently run largely true with no run-out.
A further advantage of providing the radial projections in the axially extended area of the outer part of the constant-velocity joint is that the drive and output torque is introduced into the inner ring flange at the point where the flange is directed radially outward. This torque is thereby introduced at a point of high rigidity.
As the constant-velocity joint may be designed as a sheet metal part, this has the advantage that the projections directed radially outwardly can also be formed when the part is being formed.
Less than all, and preferably every second raceway constant-velocity joint is formed as an axially extended raceway. This has the advantage that scarcely any additional production engineering costs are incurred in order to form the extension of the raceways. Here, only the raceways that are opened toward the axial extension of the outer part are extended. The raceways that are in the axial extension portion thereby form the projections that are directed radially outward.
The radial projections in the axially extended area may be produced by a stepped tool. These projections lie axially in the extension of the raceways. This has the advantage that in this area the projections can be optimized in respect of their load-bearing flanks. A further advantage is that continuous depressions can be incorporated in the inner ring flange. After fitting the outer part of the constant-velocity joint into the inner ring flange, the area of the radial projections then fits tightly in the inner ring flange. The area of the raceways bearing the load of the balls of the constant-velocity joint has the necessary clearance inside the recess in the inner ring flange.
The radial projections are situated between the outer part of the constant-velocity joint and the inner ring flange in the axial area of the inner ring flange which is directed radially outward in order to accommodate a brake disk and a wheel rim. The advantage of this axial position of the projections is that the drive torque or output torque is introduced into the inner ring flange in an area that does not have high material load stresses. The high material load stresses in the inner ring flangexe2x80x94caused by the forces introduced into the inner ring flange when cornering (reversed bending stresses)xe2x80x94are situated in the area of the transition from the wheel flange to the wheel-side inner ring. By introducing the drive and output torque directly beneath that part of the inner ring flange directed radially outward, the area in the inner ring flange highly subject to reversed bending stresses is not additionally subject to drive or output torques.
The outer part of the constant-velocity joint is fixed in the inner ring flange using a securing element. This has the advantage that the outer part can be fixed and pretensioned by the simplest of means without weakening the inner ring flange through high material load stressing at any point. A further advantage of this securing element is that it is considerably lighter than known fixing mechanisms for constant-velocity joints.
Herein, the inner ring flange may be a separate part which holds the inner ring of the bearing or may be in the inner ring itself.